A systematic review and meta-analysis of 15 prospective studies found that both short and long sleep durations are associated with increased cardiovascular risk. The analysis included 474,684 participants and 16,067 cardiovascular events, including 4,169 cases of coronary heart disease (CHD), 3,478 strokes, and 8,420 total cardiovascular disease (CVD) events. Short sleep (≤5–6 hours) was linked to higher risks of CHD (RR 1.48, 95% CI 1.22–1.80) and stroke (RR 1.15, 1.00–1.31), while long sleep (>8–9 hours) was associated with increased risks of CHD (RR 1.38, 1.15–1.66), stroke (RR 1.65, 1.45–1.87), and CVD (RR 1.41, 1.19–1.68). No publication bias was detected. Total CVD risk was not significantly increased with short sleep (RR 1.03, 0.93–1.15). Both short and long sleep durations were found to be predictors of cardiovascular outcomes. The study highlights the U-shaped relationship between sleep duration and cardiovascular health, with both extremes of sleep duration posing risks. The findings suggest that sleep duration should be considered as a potential marker for cardiovascular risk. The study also notes that sleep duration may be an indicator of underlying health conditions rather than a direct cause. The results emphasize the importance of assessing sleep patterns in cardiovascular risk assessment. The study has limitations, including potential residual confounding and the reliance on self-reported sleep data. Despite these limitations, the study provides strong evidence that both short and long sleep durations are associated with increased cardiovascular risk. The study concludes that while sleeping between 6 and 8 hours per day is not harmful, sleeping more than 9 hours may indicate underlying health issues. The study also suggests that individuals who consistently sleep 5 hours or less should be considered at higher risk for cardiovascular events.A systematic review and meta-analysis of 15 prospective studies found that both short and long sleep durations are associated with increased cardiovascular risk. The analysis included 474,684 participants and 16,067 cardiovascular events, including 4,169 cases of coronary heart disease (CHD), 3,478 strokes, and 8,420 total cardiovascular disease (CVD) events. Short sleep (≤5–6 hours) was linked to higher risks of CHD (RR 1.48, 95% CI 1.22–1.80) and stroke (RR 1.15, 1.00–1.31), while long sleep (>8–9 hours) was associated with increased risks of CHD (RR 1.38, 1.15–1.66), stroke (RR 1.65, 1.45–1.87), and CVD (RR 1.41, 1.19–1.68). No publication bias was detected. Total CVD risk was not significantly increased with short sleep (RR 1.03, 0.93–1.15). Both short and long sleep durations were found to be predictors of cardiovascular outcomes. The study highlights the U-shaped relationship between sleep duration and cardiovascular health, with both extremes of sleep duration posing risks. The findings suggest that sleep duration should be considered as a potential marker for cardiovascular risk. The study also notes that sleep duration may be an indicator of underlying health conditions rather than a direct cause. The results emphasize the importance of assessing sleep patterns in cardiovascular risk assessment. The study has limitations, including potential residual confounding and the reliance on self-reported sleep data. Despite these limitations, the study provides strong evidence that both short and long sleep durations are associated with increased cardiovascular risk. The study concludes that while sleeping between 6 and 8 hours per day is not harmful, sleeping more than 9 hours may indicate underlying health issues. The study also suggests that individuals who consistently sleep 5 hours or less should be considered at higher risk for cardiovascular events.